This invention relates to a reactor and more particularly to a reactor utilizing a plurality of pressurized fluidized beds disposed in a cylindrical vessel.
Fluidized bed reactors, usually in the form of combustors, boilers, gasifiers, or steam generators, are well known. In a normal fluidized bed arrangement, air is passed through a distributing grid, or plate, which supports a bed of particulate material, usually including a mixture of fuel material, such as high sulfur bituminous coal, and an adsorbent material for the sulfur released as a result of the combustion of the coal. As a result of the air passing through the bed, the bed behaves like a boiling liquid which promotes the combustion of the fuel. In addition to enjoying a capability for considerably reducing the amount of sulfur-containing gases emitted to the atmosphere, such an arrangement permits relatively high heat transfer rates per unit size, substantially uniform bed temperatures, relatively low combustion temperatures, and reduction in boiler tube corrosion and fouling.
Reactors of this type have taken several forms, including an arrangement where more than one fluidized bed is utilized for better control of operating conditions and load following. In these type of arrangements, when the reactor is used as a steam generator, the wall portions enclosing the fluidized beds are normally constructed of water tubes disposed in a spaced parallel arrangement and connected by fins along their lengths to serve dual purposes--to pass the water in a heat-exchange relationship with the heat from the fluidized bed and flue gas and contain the bed material within the corresponding cells. However, when dealing with pressurized fluidized beds of up to ten atmospheres of pressure, the standard waterwall configuration cannot withstand this relatively high pressure. Therefore, the walls must be specially fabricated in a costly manner or they must be enclosed in a cylindrical vessel having a circular cross-section. Since the fluidized bed enclosures have a rectangular cross-section, a great deal of lost space results when they are placed in a vessel with a circular cross section.